One of the most difficult problems to overcome in connection with interengagement between the rotor seals and the rotor housing of a rotary engine is the ability to retain a sufficient but limited amount of lubrication therebetween while at the same time provide a smoother machined surface.
Another difficult problem unique to the rotor housing of a rotary engine, is necessity for openings in the epitrochoid wall engaged by the seals, such openings comprising exhaust and intake parts, and sparking means. Severe wear and destruction occurs about these openings after a predetermined use. Yet still other problems entail providing a rotor composition which is both high in thermal conductivity and has a high hardness stable at elevated operating temperatures.
Prior art materials used for rotor housings have comprised electrolytically plated nickel-silicon carbide on an aluminum casting, chrome plating over a powder-sprayed steel coating on an aluminum casting. Each are unable to overcome the problems mentioned above and in addition the nickel-silicon carbide material is extremely difficult to grind thereby raising fabricating costs, and the chromium material requires a very slow and expensive application procedure as well as presenting pollution problems in disposal of plating wastes.